CB Annouces Closing of WCB Acquisition

Columbia Banking System, Inc. (NASDAQ: COLB, “Columbia”) today announced the completion of its acquisition of West Coast Bancorp (“West Coast”), the parent company of West Coast Bank. With the completion of the merger, Columbia’s total assets exceed $7.0 billion, with 157 branches in 38 counties in Washington and Oregon. Effective at the time of the merger, Columbia also appointed David A. Dietzler, a former director of West Coast, to serve on Columbia’s Board and the Board of its wholly owned subsidiary, Columbia State Bank.

Melanie J. Dressel, President and Chief Executive Officer of Columbia said, “We are delighted to welcome the customers, employees, and shareholders of West Coast to Columbia. The merging of Columbia and West Coast moves us significantly toward our stated objective of being the leading Pacific Northwest regional community bank. The complementary aspects of the companies’ businesses, including customer focus, geographic coverage, business orientation and compatibility of management and operating styles, makes the merger a natural fit.”

Columbia also announced the final results of the elections made by the former shareholders of West Coast regarding the form of consideration to be received in connection with the merger.

Pursuant to the terms of the merger agreement, dated September 25, 2012, former West Coast shareholders were entitled to receive merger consideration consisting of shares of Columbia common stock (“Columbia Shares”) only, cash only, or a unit consisting of a mix of Columbia Shares and cash, in each case with a value equal to approximately $24.11, depending on, and after giving effect to, the proration and allocation procedures set forth in the merger agreement.

The final results of the elections made by former West Coast shareholders are as follows:

Holders of 13,215,490 West Coast shares of common stock, (on an as-converted basis) (“West Coast Shares”) or approximately 57.5% of the outstanding West Coast Shares, made valid elections to receive Columbia Shares only.

Holders of 4,562,805 West Coast Shares, or approximately 19.9% of the outstanding West Coast Shares, made valid elections to receive cash only.

Holders of 1,970,264 West Coast Shares, or approximately 8.6% of the outstanding West Coast Shares, made valid elections to receive a unit consisting of Columbia Shares and cash.

Holders of 3,237,867 West Coast Shares, or approximately 14.1% of the outstanding West Coast Shares, did not make an election or were deemed not to have made a valid election, and will receive merger consideration pursuant to the proration and allocation formulas set forth in the merger agreement.

The cash component of the aggregate merger consideration is fixed at $264,609,560, which amount was undersubscribed, and the share component of issuable consideration (inclusive of equivalent Columbia Shares issuable upon conversion of West Coast preferred stock or exercise of West Coast warrants or options) is fixed at 12,809,525 Columbia Shares. Each West Coast Share for which a valid election was made to receive cash, or for which a valid election was not made, will receive approximately $24.11 in cash. Pursuant to the proration formula set forth in the merger agreement, former West Coast shareholders will receive approximately $4.67 in cash and 0.9397 Columbia Shares for each West Coast Share for which a valid election was made to receive stock consideration. Each West Coast Share for which a valid mixed election was made will receive approximately $12.05 in cash and 0.5831 Columbia Shares. No fractional shares of Columbia common stock will be issued; in lieu of fractional shares, former West Coast shareholders will receive cash.